How popular is Alfo?

Alfo is a rare first name for males. Alfo is an equivalently rare last name too for all people. (2000 U.S. Demographics)

Which version is better?

with its source form and related boy names. Popular varying forms of Alfo (not in Top 2000) listed in the Top 2000 are Al, Alfie, Alfons, Alfonso(#792 from current records), Alfonzo, Alford, Alonso(#731), Alonzo(#526) and Alphonse. Adoption of these forms of Alfo was well-received in the 1900s (adoption of 0.16%) and has become much lower since (adoption 0.06%, down 61%), with versions like Alonzo becoming less trendy. Alonzo is the firm favorite, although Alonso appears to be getting popular too. (2015 Birth Statistics)